I built an Android accessory using an Arduino. It's a charging dock and notification light, among other things.Electronics making apps accessory adk android droidorb electronics github house4hack open source
I have started my first open source project called DroidOrb. This is an extensible accessory for Android that most electronics hobbyists can build for themselves. The basic accessory will act as a phone dock and display notifications via the glowing "orb" in various colours. Extensions will allow the docked phone to control other systems, such as your home alarm or automation system.
For more information, please see the DroidOrb website: http://droidorb.com